Lines Matching +full:at +full:- +full:the +full:- +full:time

3 .\" Copyright (c) 2006 - 2008 Marc Balmer <mbalmer@openbsd.org>
6 .\" purpose with or without fee is hereby granted, provided that the above
9 .\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
11 .\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
15 .\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
24 .Cd "udcf* at uhub?"
28 driver provides support for the Gude ADS Expert mouseCLOCK USB and
29 the Expert mouseCLOCK USB II, receivers for the German DCF77.
30 While receivers for the British MSF time signal station are also
36 implements a timedelta sensor and the delta (in nanoseconds) between the
37 received time information and the local time can be accessed through the
40 The clock type is indicated in the sensor description:
41 .Bl -tag -width "CRITICALXX" -offset indent
43 German DCF77 time signal station
47 The quality of the timedelta is reported as the sensor status:
48 .Bl -tag -width "CRITICALXX" -offset indent
50 No valid time information has been received yet.
52 The time information is valid and the timedelta is safe to use for
56 The time information is still valid, but no new time information has been
57 decoded for at least 5 minutes due to a reception or parity error.
60 No valid time information has been received for more than 15 minutes since
79 .An -nosplit
87 Up to about 900 km, the radio signal can travel directly to the receiver,
88 providing a linearly increasing time offset based on distance.
89 Due to the curvature of the Earth, beyond this distance the signal must
90 bounce off the lower ionosphere (residing at approximately 70 km elevation
91 during the day, and 90 km at night), thus causing a non-linearly increasing
92 time offset which can only be roughly calculated using trigonometry.
93 Since the distance and transmission geometry is not known,
97 We simply assume that the offset is small.
99 In Germany, the train system uses DCF77 clocks.
100 As the distance from Frankfurt increases,